Neuro-Disruptor
The Neuro-Disruptor is a weird, WEIRD weapon. Imagine a crystal that has been carved into a shape of a gun which resembles more like some Neckbeard's dollar store space gun that goes pew pew. Except these pew pew can cause erratic seizures and brain shutdowns. It functions similiar to that of the Neural Shredder but its mechanics are beyond alien.
The Neuro-Disruptor is a psychocrystalline weapon of unknown alien manufacture, used most commonly by the Eldar Harlequins. It is a handgun made of a transparent crystalline material. It has no obvious power source, internal workings or mechanical trigger, but works by intent. It uses intricate psycho-crystalline circuitry to emit a wave of particles that disrupt the brain's neural pathways. Armour offers no protection from the Neuro-disruptor and only those of mental fortitude (Read: a battle-hardened Psyker) could resist the affects of the Neuro-Disruptor.